New England “dark day” mystery solved

On May 19, 1780, a day black as night dawned, as George Washington reportedly wrote in his diary. People thought judgment day was upon them. For 230 years, no one knew exactly what caused that dark day. Now, a recent study reveals the answer: massive wildfires. Wildfires had been suggested as a cause, but dismissed as too simple of an explanation. Erin McMurray of the University of Missouri College of Agriculture, Food and Natural Resources Tree Ring Laboratory and colleagues examined tree rings in Ontario and found evidence of massive, widespread fires in 1780 that affected atmospheric conditions hundreds of kilometers away, they wrote in International Journal of Wildland Fire.